hpl-toolkit-derive-to-node 0.0.3

use quote::quote;
use std::str::FromStr;
use syn::Fields;

pub struct HashableStruct(syn::ItemStruct);

impl HashableStruct {
    pub fn new(input: syn::ItemStruct) -> Self {
        Self(input)
    }
}

impl HashableStruct {
    pub fn render(self) -> proc_macro::TokenStream {
        let mut strct = self.0;
        let struct_name = &strct.ident;

        let mut struct_fn_to_node_stream: proc_macro2::TokenStream =
            proc_macro2::TokenStream::new();

        let mut struct_fn_to_node = vec![format!("keccak::hashv(&[")];

        if let Fields::Named(fields) = &mut strct.fields {
            fields.named.iter_mut().for_each(|f| {
                let field_ident = f.ident.as_ref().unwrap().to_string();
                struct_fn_to_node.push(format!("self.{}.to_node().as_ref(),", field_ident));
            });
        } else if let Fields::Unnamed(fields) = &mut strct.fields {
            fields.unnamed.iter_mut().enumerate().for_each(|(i, _)| {
                struct_fn_to_node.push(format!("self.{}.to_node().as_ref(),", i));
            });
        }

        struct_fn_to_node.push(format!("]).to_bytes()"));

        struct_fn_to_node_stream.extend::<proc_macro2::TokenStream>(
            proc_macro2::TokenStream::from_str(&struct_fn_to_node.join("")).unwrap(),
        );

        let stream: proc_macro2::TokenStream = quote! {
            impl ToNode for #struct_name {
                fn to_node(&self) -> [u8; 32] {
                    #struct_fn_to_node_stream
                }
            }
        };

        stream.into()
    }
}